The idea behind Groups is a good one, in theory. You can create an open or private group, and if it’s the latter, you can control who sees the information presented to members. Open groups are visible to everyone, and you can request to join a group if you can see it.

But there’s one big issue with Facebook’s implementation of groups: You can’t say no.

When I clicked on the link in the notice, I expected to be taken to a Facebook page where I could accept or decline the invitation. But no: It was not an invitation. I was immediately a member of the group, whether I wanted to be or not.

But here’s the deal: None of those folks added had the chance to say, "No thanks, I’d rather not." Yes, there’s a link on the page where you can leave a group, but you know what? You should be given that choice from the start. The protocol should be this: You are invited to a group, not pulled presumptuously into it.

As far as I can tell, there’s no privacy setting for this feature. I can’t say, "Don’t allow friends to invite me to Groups", or even, "Don’t allow me to be automatically added to a group."

It’s good to see Facebook offer features that provide more control, but the site always seems to miss some nuances of online social etiquette when rolling these out. Not being able to say no to group membership could lead to some very antisocial behavior. I could imagine being pulled into groups I’d have no desired to join, or even want to know about. And it could become the hot new way to spam Facebook users.

Update: As I mentioned in the paragraph above and elaborated in the comments, once of the issues here is being pulled into an undesirable group. Matthew Ingram, writing at GigaOM, reports that Weblogs Inc. and Mahalo founder Jason Calacanis found himself a member of a NAMBLA group on Facebook. That acronym stands for "North American Man-Boy Love Association".

Calacanis fired off an e-mail to Zuckerberg and Facebook’s CEO, Sheryl Sandberg:

I’ve now been assigned to a group that advocates… well…. ummm…. you can look it up-it’s very bad.

Also troubling:

1. I was never asked to join the NABLA group 2. I was never informed that I was “force-joined” to the NABLA group.

If you guys want to run these new features by me before you launch them, I can probably save you from a couple of privacy law suits each year.

Calacanis has not clicked "Leave Group" link on the page, so his name still appears in the list of members. I don’t know if he just hasn’t discovered you can leave a group or is staying to make a point to Facebook’s leadership. Also still showing up as a member: TechCrunch founder Michael Arrington.

The group is administered by someone named Jon Fisher, and judging from some of the content, it’s a parody, probably set up to make a point.

Point made, Jon.

Hey, Mark and Sheryl: You really need to make Group adds invitation-based, with the option to decline, rather than a process that automatically sets up membership. And you need to do it quickly.

Update 10.14.2010: The account that administered the NAMBLA page, and the page itself, have been removed from Facebook. PC World reports that it was indeed a parody set up by a friend of Arrington’s to highlight the issue of being auto-joined to a group.

Also, a Jon Fisher who says he is the chairman and CEO of Predelict Inc. and managing director of Teahupoo LLC e-mailed to say that he had nothing to do with the Facebook incident and that he isn’t even on Facebook.